Method of making reinforced refractory bodies



N. c. MOORE 3,157,722 METHOD oF MAKING REINFORCED REFRACTORY BODIES Nov.17, 1964 FiledDeG. 28, 1960 United States Patent Ollice ESYZZ PatentedNov. l?, i964 3,157,722 METHD @F lt/iAllN-G REWFGRCEED REFRACTRY BBlESNorman C. Moore, Greens Norton, England, assigner to The Plessey CompanyLimited, London, England, a British company Filed Der. ZS, 19450, No.79,0%@ @laims priority, application Great Britain, Ilan. 6, 1196i?,ded/ell d Claims. (Cl. 2nd-266) This invention relates to methods ofproducing refractory bodies by the ejection, or projection of, particlesor droplets of molten refractory material onto a suitably preparedsurface. It is known to form bodies of refractory material by depositinglayers of the material onto a prepared surface so as to build up therequired body. Layers of refractory material `are deposited byprojecting molten droplets or particles of the refractory material ontothe surface to be coated so that the droplets soldify on contact withthe surface. lf such a coating is deposited onto a prepared combustiblebase, for example graphite, which is subsequently removed for example byan oxidation process a porous refractory shape may be prepared which hasthe same profile as the base material.

One such method of projecting the molten particles or droplets is knownas flame spraying. ln this process the refractory material is fed intothe llame of a flame spray gun wherein the material is melted and iscarried along with the flame towards the surface against which the flameis directed.

lt has been found that cooling occurs very rapidly in consequence littledow of the refractory material can occur before solidilication, and theresulting coating has been found to be somewhat porous.

In my earlier specification (reinforced ceramic mate rial British patentspecification No. 947,576) we have described methods by means of which arefractory body is reinforced by the introduction of foreign bodies of ametal or non-metal nature. ln particular we have dcscribed the inclusionof metal bres, silicon nitride whiskers and metal wire.

Broadly according to 'a first aspect of the present invention there isprovided a ceramic body which is reinforced by a continuous length ofmetal wire integrally united with the ceramic body during the formationthereof.

Broadly according to a further aspect of tre present invention there isprovided a method of forming a reinforced ceramic refractory body byprojecting molten particles or molten droplets of the refractorymaterials onto a suitably prepared and shaped surface, whilst simultanoously winding a metal wire onto the deposited refractory material sothat the wire becomes embedded into the material.

For a better understanding of the invention one method of forming -acylindrical body having a spirally wound metal wire reinforcement willbe described in greater de' tail in relation to the `accompanyingdrawings, in which FIGURE l schematically illustrates Ithe method, and

FIGURES 2 and 3 are sections of a reinforced ceramic body, FlGURE 2being a section on a line ll-ll of FGURE 3 and FGURE 3 being a sectionon the line III-Ill of FIGURE 2.

A cylinder l having an external diameter substantially equal to therequired internal diameter of the cylindrical ceramic body 2 is formedfrom a wire gauze, for example of stainless steel With 40 mesh. Thecylinder l is mounted on a suitable mandrel or other rotatable support 3for rotating the wire cylinder l about its longitudinal axis, at apredetermined speed. The means for rotating the mandrel is not shown.One suitable means is la lathe,

turntable, or electric motor With a suitable chuck for gripping themandrel.

ln the present instance it will be presumed that it is desired to form arefractory body of alumina. If this is the case an initial coating ofalumina, i.e. la thin layer (not shown) of alumina powder in a suitablebinder is applied to the wire cylinder l so as to ll the interstices ofthe wire gauze former. The ceramic material to be sprayed is projectedtowards the thus prepared gauze by means of a llame spray gun d or anyother mthod of particle projection for example :a plasma spray gun orother means for introducing the ceramic particles into the flame. Thewire gauze former is progressively `rotated and the spray gun flame 5 issimultaneously reciprocated longitudinally of the former as indicated bythe arrows 6 so as to obtain an even deposit of alumina. Simultaneouslywtih the movement of the spray gun d and the rotation of the wire gauzeformer l a continuous length of metal Wire 7, for example tungsten wire,is wound on to the former. The winding-on of the wire is such that thewire engages with the former or the previously deposited layers of thealumina prior to being subjected to the effects of the hot llame. Thewire 6 is fed from a suitably positioned bobbin 3, which latter isrotatably mounted in a support 9.

The process is continued until a desired thickness of the refractorybody 2 is obtained and also the requisite number of turns or layers ofthe wire '7.

The wire 7 is fed through a tube lll through which an inert gas, forexample argon, is owing thereby preventing any oxidisation of the wire 7prior to its being subjected to the effects of the spray gun. The tubeis progres sively reciprocated in unison with the gun so that the wireis always fed into the llame 5.

The direction of reciprocation is shown at ll.

After the refractory body has been formed it is removed from themandrel. The wire gauze l can be removed by any convenient manner forexample by fa chemical process or 1a grit blasting process.

The refractory body 2 thus formed is reinforced by the wire 7. lnaddition, the wire 7 can serve for a second purpose for example as aresistance wire or as the turns of an inductance coil, thereby providinga resistance or inductance which may be used at high temperatures.

ln the case of the spraying of the alumina, the spraying conditions canbe such that the finished refractory body is in a metastable state forexample in the gamma form or in the stable state that is the alpha form.

It will be appreciated that by changing the diameter of the wire or thetype of wire during the formation of the refractory body it is possibleto form refractory bodies having different reinforcement characteristicsiand/ or different electrical properties at different sections thereof.

Furthermore, the metal wire can be wholly or partly replaced by means ofmetallic or non-metallic whiskers which have been produced in the formof a spun thread. In the earlier specification already referred. to theterm Whisker has been explained.

ln contrast to the formation of a cylindrical or other body ofrevolution which may be formed by a winding or rotary action of themandrel 3 it is possible to reinforce at plates by laying the wirereinforcement backwards and forwards across the plate as it is beingformed so as effectively to form an extended layer of the wire in atleast one plane of the plate.

Furthermore, it is possible to move the Wire guide that is the tube llt)so that the wire 7 can be laid onto the body 2 being formed inaccordance with certain wire laying formations, such as; one which ishelically arranged with respect to the axis of the body being formed; anArchimedian type wire in the case where the body being formed is asurface of revolution such as for example a hemisphere or a hemisphereconcated cone or the like.

If desired more than one wire could be laid simultaneously onto the bodybeing formed.

If desired more than one spray gun can be used in the formation ofthebody.

What I claim is:

1. A process for making va ceramic refractory body including mechanicalreinforcement consisting of fibrous material comprising the steps ofheat spraying a fusible ceramic material so that it becomes deposited ina substantially unchanged chemical condition onto a former andsimultaneously incorporating therewith the brous material in the form ofa lament allowing the ceramic to coorlrand solidifying,andVsubsequentlyrremoying resulting refractory body from former,

2. A process as claimed in claim 1 in which at least part of the fibrousmaterial is a metal wire.

3. A process as claimed in claim 2 in which the metal wire is protectedfrom atmospheric oxidation by means of a non-oxidising gas stream beforeit is incorporated in the ceramic body.

4. A process for making a ceramic refractory body of Mccuuogh 156-1722,005,897 6/35 Knowles 154-90 XRV 2,272,342 2/42 Hyde. y

2,674,678 4/54 Wakefield '117-129 XR 2,676,899 4/54 Hackley L--117-f-129 XRM' 2,699,415 1/55y Nachtman 156-173 2,844,693 7/58 Rigterink117-231 2,848,794 8/58 Roth 117-4231 2,974,388 3/61 Ault 25-1563,056,184 10/62 Blaha 25-156 EARL M. BERGERT, Primary Examiner.

CARL F. KRAFFT, Examiner.

1. A PROCESS FOR MAKING A CERAMIC REFRACTORY BODY INCLUDING MECHANICALREINFORCEMENT CONSISTING OF FIBROUS MATERIAL COMPRISING THE STEPS OFHEAT SPRAYING A FUSIBLE CERAMIC MATERIAL SO THAT IT BECOMES DEPOSITED INA SUBSTANTIALLY UNCHANGED CHEMICAL CONDITION ONTO A FORMER ANDSIMULTANEOUSLY INCORPORATING THEREWITH THE FIBROUS MATERIAL IN THE FORMOF A FILAMENT ALOWING THE CERAMIC TO COOL AND SOLIDIFYING, ANDSUBSEQUENTLY REMOVING RESULTING REFRACTORY BODY FROM FORMER.